The present invention relates to a novel valve design for controlling fluid flow. More specifically, the present invention relates to a fluid flow valve that incorporates an elliptically shaped flow control member.
Active combustor stabilization control in a turbine engine may include the use of several fluidic valves located about the annulus of the engine combustor. Also, desirably, the opening and closing rate capability of such valves should be on the order of xc2xd kHz to 1 kHz. However, typical available valves are capable of operating only up to about 300 times in one second.
U.S. Pat. No. 3,174,716 suggests the use of a bowed spring for variably restricting a pressure port in response to magnetostrictively generated changes in the location of one end of the spring. This patent also suggests magnetostrictively generated changes in the separation between the ends of a bowed spring to control the opening and closing of a pair of electrical contacts. The patent points out that the bow spring amplifies the relatively small magnetostrictively generated dimensional changes to allow practical use of those changes. Magnetostrictive actuators require the continuous application of power to maintain their activated position. Additionally, the gain of magnetostrictive materials decreases significantly with increasing temperature. Finally, the overall life of the spring element is shortened by the preloading required by the magnetostrictive actuator.
A number of piezoelectric valves have been proposed for these purposes, which embody a valve element in the form of either a circular disc or a beam. The circular disc or beam element is usually a laminated structure having a piezoelectric ceramic wafer bonded to one or both major surfaces of a substrate having a different coefficient of expansion from the wafers. Alternatively, the valve element may comprise two oppositely polarized piezoelectric ceramic wafers of differing coefficients of expansion and bonded to each other in face to face relationship. Application of an electric field to the wafers causes the so constructed element to deflect in the same way as a bimetallic strip.
U.S. Pat. No. 4,545,561 describes and claims a piezoelectric valve for controlling fluid flow. The valve includes a split or two part housing between which parts a shallow and generally cylindrical cavity is formed. The split housing is divided along a parting plane that is parallel to opposite circular end planes of the cylindrical cavity. One part of the housing includes inlet and outlet fluid apertures for incoming and outgoing fluid whereas the other part of the housing contains first and second flexible electric contact elements connectable to opposite terminals of a voltage source. A deformable conductive plate element is captured at its perimeter between the two parts of the split housing and has a piezoelectric wafer bonded on that side thereof opposite from the fluid apertures and in a position proximate to the center of the plate element such that the piezoelectric wafer is supported by the plate element without contacting the housing at its perimeter.
When assembled, the first flexible electric contact element is pressed into electrical contact with the piezoelectric wafer and the second flexible electric contact element is pressed against the deformable conductive plate element so that, upon actuation of the piezoelectric element by the voltage source, the plate element is caused to travel between a first position in which the plate element occludes the passage of fluid between at least one of the fluid apertures and the cavity and a second position in which the plate element is deformed away from at least one fluid aperture allowing fluid flow through the cavity between the inlet and outlet apertures.
It will, therefore, be appreciated that the valve described in U.S. Pat. No. 4,545,561 is an example of a circular disc type piezoelectric valve in which the disc is captured at its perimeter. On the other hand, a beam element, sometimes referred to as a bender element, type piezoelectric valve is described and claimed in PCT Application WO86/07429. The valve according to WO86/07429 comprises a housing defining a cavity, an inlet conduit means having one end terminating as an inlet orifice, said inlet orifice having a cross sectional area and being at a predetermined location and within said cavity and having another end of said inlet conduit means in fluid communication with a fluid supply; an outlet conduit means having one end terminating as an outlet orifice at a predetermined location within said cavity and said outlet orifice having a predetermined cross sectional area, another end of said outlet conduit means in fluid communication with a means for using fluid from said fluid supply and having an effective fluid storage volume, a bender element appropriately positioned within said cavity and affixed to said housing means, having a means adapted for providing signal communication between said bender element and a controllable flow control signal, said signal effective to cause said bender element to deflect a controlled amount thereby permitting an amount of said fluid to flow at a controlled flow rate through said valve device; and a first sealing means affixed to said bender element to effectively seal, during the absence of said flow control signal, said outlet orifice.
These devices are what is known as two state valves, that is, they are either open or closed. Metering of the fluid flowing through these valves is accomplished by rapidly opening and closing the flow opening. While this approach to the problem of accurate fluid flow control is interesting, there is still a current and continuing need for valves that accurately control the flow of fluid through the valve. Moreover, there is a current and continuing need for a valve that provides analogue type control over the fluid control as opposed to digital or quantum control. Further, it is desirable to provide a short path length and a large area aperture between inlet and outlet plenums of a valve. It is still further desirable to create a high rigidity, low inertia, and therefor, rapidly responding, valve configuration.
It is an object of the present invention to provide a valve comprising a valve body having a fluid inlet port, a fluid outlet port, a cavity with flow control surfaces; and a valve mechanism comprising at least one flexible spring strip, each coupled to the valve body and anchored in place at one end relative to the valve body and permitted one degree of freedom, or movable, at another end relative to the valve body.
It is another object of the present invention to provide the valve described above further including an actuator mechanism coupled to the movable end of the flexible spring strip.
It is yet another object of the present invention to provide the valve described above further including an adjustment mechanism coupling the anchored end of the at least one spring strip to the valve body.
It is still yet another object of the present invention to provide the valve described above wherein the adjustment mechanism includes a mechanism for nominal flow adjustment.
It is a further object of the present invention to provide a valve as described above wherein the at least one spring strip is elongated with an anchor end and an adjustment end and further comprises a flow blocking dam located approximately between the anchor end and the adjustment end.
It is a still further object of the present invention to provide the valve as described above wherein the at least one spring strip further includes at least one flex facilitating detail located adjacent at least one of the anchor end and the adjustment end.
It is a still yet further object of the present invention to provide the valve as described above further including an anchor flange located at the anchor end and an adjustment flange located at the adjustment end of each of the at least one spring strip.
The novel features that are considered characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its structure and its operation together with the additional object and advantages thereof will best be understood from the following description of the preferred embodiment of the present invention when read in conjunction with the accompanying drawings. Unless specifically noted, it is intended that the words and phrases in the specification and claims be given the ordinary and accustomed meaning to those of ordinary skill in the applicable art or arts. If any other meaning is intended, the specification will specifically state that a special meaning is being applied to a word or phrase. Likewise, the use of the words xe2x80x9cfunctionxe2x80x9d or xe2x80x9cmeansxe2x80x9d in the Description of Preferred Embodiments is not intended to indicate a desire to invoke the special provision of 35 U.S.C. xc2xa7112, paragraph 6 to define the invention. To the contrary, if the provisions of 35 U.S.C. xc2xa7112, paragraph 6, are sought to be invoked to define the invention(s), the claims will specifically state the phrases xe2x80x9cmeans forxe2x80x9d or xe2x80x9cstep forxe2x80x9d and a function, without also reciting in such phrases any structure, material, or act in support of the function. Even when the claims recite a xe2x80x9cmeans forxe2x80x9d or xe2x80x9cstep forxe2x80x9d performing a function, if they also recite any structure, material or acts in support of that means of step, then the intention is not to invoke the provisions of 35 U.S.C. xc2xa7112, paragraph 6. Moreover, even if the provisions of 35 U.S.C. xc2xa7112, paragraph 6, are invoked to define the inventions, it is intended that the inventions not be limited only to the specific structure, material or acts that are described in the preferred embodiments, but in addition, include any and all structures, materials or acts that perform the claimed function, along with any and all known or later-developed equivalent structures, materials or acts for performing the claimed function.